Exporting Vertices from Blender 2.8 to a .txt-File to import it in ArchiCAD as Terrain
blender uses python

if your terrain is meshable here's a snippet to reveal vertices for a mesh. 

import bpy

def reveal_vertices(mesh):
    verts=mesh.data.vertices
    for i in range(0,len(verts)):
       print('vert['+str(i)+']: '+str(verts[i].co))

mesh = bpy.context.active_object
reveal_vertices(mesh)


about the storing-vert-coordinates-in-a-text-file part that would just be a 
basic python problem but google is always a friend